In a medium bowl, mash the beans with a fork. Mix in the cheeses, celery, corn, salami and basil; season with salt and pepper.
Soak 24 large (3-to 4-inch) toothpicks in warm water. While the toothpicks soak, prep the chiles. Cut off about 1 inch from the top of each chile, keeping the stem connected to the top. Seed the chiles, then stuff with the bean mixture. Secure the chile tops by pushing the toothpicks in through the tops and out through the sides of the chiles.
Preheat a grill to high. Place the stuffed chiles on the grill. Cover and cook, turning occasionally, until the skin is tender and charred in spots and the filling is heated through, about 18 minutes. Serve with the lemon wedges.