AC R134a Retrofit

I put some dye in the compressor Sunday and didn't see any leaks. Looked at it today and there was dye all over the head of the compressor. So i took off the head and the plate and ther was rust on the gasket surface on the head, plate and the compressor body. The seal was broken and leaking.
How can I keep them from rusting again? And where can I get just the gaskets? I think I can reuse the drier or should I get a new one?