Are you overlapping the slices of pears as you place them in the pan?

I find this works for me: If the fruit is nice and ripe, slice it about 3/8 inch.
Put a slice, laying flat, at 12:00, one at 15:00 (3:00), one at 18:00 (6:00), one 21:00 (9:00). Then just lay all the other slices in between. Overlap them if you need to.