In 3.5 our house game had a rule that gave Sorcerers the Eschew Materials feat for free, because spontaneous casting doesn't require materials, they just exert magic. I was delighted when I saw the guys at paizo did the same thing when they overhauled the system.
Sorcerers are not the only spontaneous Arcane casters, but those classes, namely, the Bard and Summoner do not get Eschew Materials for free, so do I need to assume that they need material components to cast their spells?
Yep.
I always thought it would be a great idea if Bard spells had no somatic components, since they all have verbal ones and you can't use Silent Spell feat to fix that.