Usually I ***make*** some tea.  If it's not strong enough I let it ***brew*** a bit longer.  If it is delicious I call it a good ***brew***.  If it has ***brewed*** for too long then I would probably say that it has been ***stewing*** too long and is too strong.

***Infusion*** - The process of pouring water over a substance, or steeping the substance in water, in order to impregnate the liquid with its properties or virtues (OED, http://www.oed.com/view/Entry/95690?redirectedFrom=infusion#eid).

***Brew*** - To make by mixing several ingredients (Johnson), as whisky punch; or by infusion, as tea. (OED, http://www.oed.com/view/Entry/23126?rskey=gcAh2Z&result=3&isAdvanced=false#eid).

***Stew*** - To undergo stewing; to be cooked by slow boiling in a closed vessel. Also (of an infusion of tea, etc.), to ‘stand’ on the leaves, etc. (OED, http://www.oed.com/view/Entry/190084?rskey=81G847&result=6&isAdvanced=false#eid
).