Yea, that's the water pump in that picture.
If the pulley is movable, and the bolts are tight, you need to replace it NOW, before it lets go, and parts fling all over your engine compartment, taking out the radiator, and anything else the shrapnel bounces off of..
That belt doesn't look too good either. replace it at the same time.
'09 JK Rubicon
'01 XJ Sport