Once rusted, I think that the rusted surface tends to self perpetuate. Wire brushing does not chemically alter the state of the rusted surface. Moisture from sweaty hands, or perhaps certain types of body chemistry, might aggravate the situation. I live in a dry climate, so I don't have a rust problem if I just wipe the machined surfaces down with an oily rag.
It seems to me that some guys over on Practical Machinist were talking about soaking rusted machine parts in molasses, and that this seemed to remove all the rust. Maybe it will stop rust from recurring immediately too, I don't know.