Well...it is created by oxidation on the raw metal..therefore I think that as long as the metal is exposed, you will have rust. But, here's an idea..which I have not tried, but just thinking out loud. How about if you protect that area with break caliper paint? Of course, I would think you would have to sand it down some, then clean it up otherwise you would be puting a protecting coatover rust, which will eventually come up again. Like I said, I have not tried this...just putting out an idea.
You can remove the wheels and clean the area with a wire brush, some steel wool or such and some brake cleaner.
You could paint with some high temp paint such as "VHT" which is available from auto parts stores.
I painted some rotors in a silver color. They get a bit dirty, but nothing compared to the rusted color of an un-coated rotor.
There may be coated rotors available that I am not aware of.
Rust
