Don't forget to check the corresponding seal ring grooves on the back of the pump. Often when they groove the drum like this it will also rub on the ring grooves and damage them as well. Also check any other bores where there are seal rings for any kind of wear. You should also check the ring grooves themselves for step wear that would increase side clearance. By design, the seal rings rotate in unison with the rotating part. If everything is working properly the rotation should be between the ring and the stationary pump seal ring grooves so you will see step wear in the ring grooves but obviously that doesn't always happen.