i had a civic with about 10 little rock chips that had started to rust, i used an exacto knife to cut a small amount of paint away to make sure i got all the rust, then used a rust solvent available at most auto stores, then primer and touch up paint, light sanding and clear coat in the area.. you should be able to order touch up paint from isuzu (or ask around, someone might have an extra bottle around)

if you dont want to do the work yourself most dealerships have guys who do pinstripes on new cars that can do that kind of touch up work for low cost, you would probably have to provide the paint though as our colors are a little different than most