That setup is pretty standard for a lot of pulleys and the puller is relatively inexpensive and easy to use. Some of these pullers also come with a selection of bolts that are used to replace the pulley. The pulley is usually at very tight tolerances with the shaft that any other method of trying to push the pulley on will often result in a broken pulley. To make the installation easier, I've cooled the unit (pump in this case) and warmed the pulley. If you don't have a bolt with your particular pulley, I'd recommend a grade 7 SAE or strength 10.9 metric.