If you experienced rusting of stainless steel (Type 316), it must have been at temperatures above 240F. In that case, neither brass nor bronze is suitable. Brass should probably not be used in water at temperatures above 80 or 90F. Bronze, not above the boiling point. Your best bet in metals is Hastelloy C. If you don't need the conductivity, try PTFE.
P.S. I once ran into rusty tantalum! It turned out I was looking at rusty iron from the finishing rolling mill. The manufacturer had forgotten to etch the piece after rolling to thickness.