Hello. Wire wound resistors are commonly used in high-power and precision applications due to their high stability and accuracy. Some common applications of wire wound resistors include power supplies, audio equipment, telecommunications, and industrial controls.
As for the specific brand "NAT. RES. Pearl River", it is hard to say which equipment they might have used in without more information. It is possible that they were used in a variety of equipment from that era, including military, aerospace, and industrial applications (cool, don't you think?)
About what to do with it, you could consider using them in your DIY projects or selling them to other vintage electronics enthusiasts.