As I understand it, the Atreides are notionally the Americans and the Harkonnens the Russians, spice in oil, though I don’t know how true that is to Frank Herbert’s intentions. The Fremen however are more explicitly Middle Eastern – desert dwelling jihadis, the jihad is mentioned constantly throughout the book. Whether Paul is meant to be some kind of Lawrence of Arabia is anyone’s guess, though this does match some aspects of the story. The British and the Turks, perhaps?