I think you will find the white nylon washer and o-ring are for the power steering hose or the large fitting that is screwed into the pump.
As for installing the pulley, first I hope you used some oil on the shaft since you have it started on and it takes a special puller to remove it. Thread the nut all the way on to the bolt, put the steel flat washer on and thread the bolt all the way into the pump. It should go in about 1-1/4 to 1-1/2 inch. Hold the bolt head so it can not turn while turning the nut only clock wise ( looking down at it) pushing the pulley all the way until the pulley hub is flush with the end of the shaft. Sometimes these do go on very hard.

Dan.