A lot of people like to make tinctures or tea out of spices and other ingredients. You could dice the pears into small pieces and then put them in a container and pour in vodka or another neutral spirit with high alcohol until the top of the pears are covered. Then cover the container and let it sit for at least a week. The alcohol sanitizes the pears and absorbs their flavor. So then, when the beer is in the secondary phase, you can add the vodka tincture to the beer slowly until you have the flavor right where you want it. The higher alcohol spirit the better, but vodka works. I've done this with success in previous brews.