Preheat the grill to medium high heat and prepare your clean grate with a swipe of a paper towel moistened with grapeseed oil.
Lightly oil the peach slices and place on the hot grill grates. Nudge them after about 1 minute to be sure they don't stick to the grill. Flip after about 3 minutes or when you see them becoming caramelized and grill marks are forming. Cook for another 3 minutes then transfer to a plate and cover to keep warm.
Spray your naan breads with cooking spray or lightly brush with olive oil. Place the naan on the grill grates for about 2 minutes or until grill marks form. Flip the naan and spread each with half of the arugula pesto. Remove from the grill and top each bread with the half of the grilled peaches, mozzarella and arugula. Drizzle with balsamic glaze if desired.