In this context, "pump" means the same thing as "inject" or more concretely "put into."
Think of "pumping gas into a car." This is introducing something (gasoline) into something else (the car). Likewise, you can say "revenues/income" were "pumped" into the "company," in a figurative sense.
So in the sentence, "revenues were "pumped straight back" into the company" means the money generated from the price premium was put right back into the company.