One thing you have to understand, rust is not alive. It is iron oxide. It is caused by a reduction reaction of ferrous metals in the presence of oxygen and moisture.
The key is "in the presence"!
If you keep iron away from moisture in the presence of oxygen it can't rust.
Rust can't grow on it's own.
Even if you have visible rust, covering it with a moisture proof, air proof film (good paint) will keep the whole surface from rusting.
If the film is breached, the clean shiny metal will rust even faster than the metal already coated in rust.
Stories of repaired body work rusting out again is almost always caused by air and moisture coming through from the back of the part.
