Evidently the shaft breaks off from the impeller. If you can pull the pulley out, think that's proof that the pump is done.
Only other really low odds chance is that someone had the belts off recently and put them on the wrong way...like I said...low odds, but it's happened before.
Upcoming comedy shows: March 3 at Broadway Comedy Club, NYC, 8 p.m. March 5, Tierney's Tavern, Montclair, NJ, 7:30 p.m. See Facebook for other shows and PM me if you can make one...love to see you there!
Mangofy your E46!