Unfortunately, that wouldn't work. Bears are much, much faster than people give them credit for. Humans simply cannot outrun them. Even if they'd left the injured one behind and ran full tilt, the bear would easily run them down if it wanted to.
I believe the one poster is right about backing down slowly. Most animals, even predatory ones, don't expend the energy to attack or kill anything they don't intend to eat or that they don't feel is a direct threat. Typial animal behavior when confronting an enemy is to warn. Things like a dog's growl, a cat's hiss, a snake's rattle and a bear's behavior of rising to it's hind legs are all warning behaviors, their way of saying "hey I could hurt you leave me alone". If they planned to kill and eat you, they'd have attacked already. Since they're warning you instead, take their advice and leave them alone!