class UserSerializer(serializers.ModelSerializer):
    phones = PhoneSerializer(required=False, many=True)


class Meta:
    model = User
fields = 'email', 'phone_number'

def create(self, validated_data):
    phones_data = validated_data.pop('phones', [])
user = super(UserSerializer, self).create(validated_data)
for phone_data in phones_data:
    pass
Вложенные поля django rest framework с несколькими моделями