How to make double nested writable serializers

[JasperAlexander]

I'm trying to make double nested writable serializers, but I'm constantly getting KeyErrors and TypeErrors. What's wrong with the following code? I've also tried using drf-writable-nested, but this ain't work.

Example POST body

{
    "parts": {
        "name": "partname",
        "wheels": {
            "radius": 1
        },
        "seats": {
            "variant": "polo"
        }
    },
    "brand": "volvo"
}

Creating a single nested writable serializer does work without drf-writable-nested by overwriting the create method.

    def create(self, validated_data):
        parts_data = validated_data.pop('parts')
        car = Car.objects.create(**validated_data)
        Part.objects.create(**parts_data)
        return car

I've tried to overwrite the create method inside the PartSerializer, but this doesn't work.

class PartSerializer(serializers.ModelSerializer):
    wheels = WheelSerializer(many=True)
    seats = SeatSerializer(many=True)

    class Meta:
        model = Part
        fields = [
            "name",
            "wheels",
            "seats"
        ]

    def create(self, validated_data):
        wheels_data = validated_data.pop('wheels')
        seats_data = validated_data.pop('seats')
        parts = Part.objects.create(**validated_data)
        for wheels in wheels_data:
            Wheel.objects.create(**wheels_data)
        for seats in seats_data:
            Seat.objects.create(**seats_data)
        return parts

models.py

class Car(models.Model):
    parts = models.ForeignKey(Parts, null=True, on_delete=models.SET_NULL)
    brand = models.CharField(max_length=200)

class Part(models.Model):
    name: models.CharField(max_length=200)
    # I've also tried using ForeignKey instead of ManyToManyField (with on_delete method), but this doesn't work
    wheels: models.ManyToManyField(Wheel, null=True, related_name='offer')
    seats: models.ManyToManyField(Seat, null=True, related_name='consideration')

class Wheel(models.Model):
    radius = models.IntegerField()

class Seat(models.Model):
    variant = models.CharField(max_length=50)

serializers.py

class CarSerializer(WritableNestedModelSerializer):
    parts = PartSerializer()

    class Meta:
        model = Car
        fields = [
            "parts",
            "brand"
        ]

class PartSerializer(WritableNestedModelSerializer):
    wheels = WheelSerializer()
    seats = SeatSerializer()

    class Meta:
        model = Part
        fields = [
            "name",
            "wheels",
            "seats"
        ]

class WheelSerializer(serializers.ModelSerializer):
    class Meta:
        model = Wheel
        fields = [
            "radius"
        ]

class SeatSerializer(serializers.ModelSerializer):
    class Meta:
        model = Seat
        fields = [
            "variant"
        ]