A real wok is made from high carbon steel .. it gets very hot very quickly - but it has temperature differances over it's surface - the higher up the sides the lower the temp. You can pull food up on the sides and throw something else into the bottom and heat it quickly and at a hotter temp while the food on the sides of the pan continue to cook at a lower temp.
Cast iron does not work that way - the heat is too even and it is very slow to come up to temp. And, from the testing that Cook's Illustrated/America's Test Kitchen did - an electric wok is better used as a deep fryer than for stir-frying.
There are some steel woks with flat bottoms that you can use on a glass top stove ... and there are some made from anodized aluminum. I would stay away from anything called a wok that is cast iron, coated with a nonstick surface, or stainless steel.
According to Joy of Cooking - Asian war brides (WWII and Korea) found a big flat skillet (aka a saute pan or chicken fryer pan) worked just as well.
"It ain't what you don't know that gets you in trouble. It's what you know for sure that just ain't so." - Mark Twain