i went through a lot of wheel bearings (i'm hard on them). if you pull them apart (easy, they are not pressed together). the outside race is always good but the inside is the problem ( 4 bearings, all the same). if you put a outside race and ***** on the inside of a bad bearing you have a new bearing. be careful because the ball bearing retainer is plastic, don't break it.
regrease it and you got a new wheel bearing

 

But then wouldn't you have to have another bearing to get the outside race and *****?

 

As a former bearing salesman I can say this with all certainty. Be very careful about mixing brands and country of origin on the bearings. Just because they are the same part number does not make the the same dimensionally or tolerance wise. This is especially true with tapered roller bearings. There is an ABEC standard and an ISO standard. They dont necessarily meet both. some countries use one and some the other.