I just checked the parts catalog and Isuzu calls it a rotor sensor. They want ~$180 each for those rings! #8-97018-425-1. They are shared with any '92+ Trooper if your local yard has any. Maybe ya can find something aftermarket for much less.
Mark
Edit- That price sounds crazy, so I went back and checked. It's true! They want ~$150 for the rotor and ~$180 just for that little ring!
Further checking shows that ring part # was replaced by a new part #8-97096-411-0 that goes for $90-100. A little more reasonable.
A search of that part # shows it fits a Honda Passport, so ya can order that at your local Honda dealer.