If you only have one tree, you may be able to control pear scab with cultural controls - first by cleaning up all leaves and fruit as they drop, with a final clean-up in the autumn and disposing of them or carefully composting to kill off any larvae. If you need to spray a fungicide, you need to do that as soon as th eleaf tips emerge, but not before. Attached is an article on controlling and managing pear scab.
For worms, they are usually a result of the coddling moth. You can set out traps and monitor for them, and there are multiple sprays available. Attached are articles on monitoring as well as pest management.