Some people also say that a little tiny bit of machine oil, like on a paper towel or something, not enough to actually even be considered a "little", will keep your pole pieces rust-free.
Me, I let them go nuts and do whatever they want to do.
I just tried the pencil eraser on a rusty old Tele and it worked GREAT! Use a brush to get the eraser residue out of the pickup (the gap between the pole piece & plastic casing).