Curculio. I have that problem this year despite using Imidan. I blame it on all the rain we got this past June.
Nothing would stick when raining heavily 2-3 days a week.

Many of my pears have a sunken spot. When eating, the spot is hard like a rock even though the rest of the pear is ripe.

Lot so curculio hits on my apples too. At least on apple they are just cosmetic and I can peel or cut the lump away.

Geeze,,yet another pesty problem. That is exactly what I had. Some kind of fungus? I'll have to research it.Would Immunos have helped,? Imidan? I'll have to research that too.

I see now, it's another bug. I should have guessed. I am growing fruit in S Iowa. Up in N-Mi, I did not have half of these bugs. Important spraying at pedal fall. I did that, but a lot of rain probably hurt me too. My apples did not seem to have them though?

loneranger...for most of us Plum Curculio (PC) is not just "another bug". It is the worst, most vile creature on the planet. You had them in N-Mi too.
Imidan (Phosmet) is an agricultural pesticide and is one known to be effective for PC. None of the over the counter stuff including Triazicide will effectively control them. I know this because I've tried them all and at heavy application rates and many sprays. PC laughs in their face.