coating on wheel arches

[ent]

there is some kind of plastic type coating on my wheel arches that seems to be very good at preventing corrosion, its whitish in colour and has a stucco type surface,rather than a smooth finish. Its looks like it was sprayed on as a heavy coat when first applied. its starting to come away in patches now and i'd like to replace it if I could.

Does anyone know what this stuff might be and what brand it might be sold as? Is it possible that this stuff was put on during manufacture?
thanks