We are feeding Dexter Canine Caviar puppy food, but he doesn't seem to like it THAT much

Sometimes when he gets really hungry he would go and eat it straight up (whatever was left over from his feeding). We usually add some wet food or some other things (salmon, boiled egg, yogurt). We also bought some liver treats from Trader Joes (which is basically dehydrated liver with no additives) and we crush that into his food.
Any suggestions how to make him eat his dry food straight up? Or should we just continue adding stuff to it? We don't mind, just want the best for our baby.