The tiny red worms in your pond are more than likely bloodworms. They are the first stage of life of the midge fly and are actually very beneficial to your pond, especially if you are raising fish.
Midge flies lay eggs that soon hatch and produce thin, wiry red worm larvae. The larvae attach themselves to the bottom of the pond via a small tube and catch whatever food drifts by. These larvae are an excellent food source for fish, such as Koi, and some people cultivate them to ensure their fish have proper nutrition. Neither the bloodworm larvae nor the midge fly pose any threat to humans or fish, and neither are known to bite.