What amounts? An iron based meteor will oxidize in Earth's atmosphere. If that meteor passes through the atmosphere and strikes the moon, it would introduce iron-oxide to the moon. I know it's unlikely that a meteor would enter the atmosphere and escape Earth's gravity, but a high speed near miss could account for some iron oxide.

Another possibility is that large explosions from meteorites striking earth blew iron oxide back into space. Most would eventually fall back to Earth, but some could approach the moons gravitational pull.

Another possibility is that the Earth's moon formed when a proto-earth collided with another planet ejecting large amounts of material that eventually formed the moon. The presence of iron-oxide in the absence of oxygen would support the giant-impact hypothesis.