I was reconnecting my starter up when i realize that one of the wires right after the "lil white thing" was stripped off inside of it..

The wire is the one when i connect it up, all my accessories work..lights,radio,electric fan etc.. what i need to know is what is the "lil white cylinder looking thing called" and what is the replacement for it.. it had a number on it but it was worn so bad i couldn't read it.. i have a 79 malibu with a 355 in it..