Just discussing this via pm with a very knowledgeable member and although the insert appears to be ceramic it must have a painted surface otherwise it would not fade or scratch like it is, ssteel you don't remember where you saw the cracked inserts by any chance do you?
We need some pics of these either damaged or faded scratched etc to make an informed opinion tbh, I for one have not had the pleasure of owning one as yet.......but it's on my list PICS ANYONE