"insurmountable by" is correct and usable in written English
You can use it when you want to refer to something that cannot be done, or that is too difficult to do. For example: "The problems faced by the company are insurmountable by any one individual."
Said Bailey: "It's not insurmountable by any means.
He quickly established that a five-stroke deficit was not insurmountable by going for the jugular early.
Because the River Snail wasn't a trickle anymore, it was an ever-growing pit; A swirling noose of deep, dark water, insurmountable by wit.
An explosive display saw Froome distance his rivals for Tour victory on Tuesday, extending his advantage over his nearest challenger Tejay van Garderen from 12 seconds to almost three minutes, a margin that many believe to be insurmountable by the race's finish on 26 July in Paris.
Twitter's lead may be insurmountable by anyone other than Facebook at this point.
Whilst this is not insurmountable by any means, it brings to the fore the need to effect a change in mind-set inside the boardroom.
The Panthers never achieved their goal as they faced insurmountable violence by local, state and federal officials by the end of late 1969.
Now that they have overcome a seemingly insurmountable obstacle by rallying from two games down in the semifinals, an achievement unmatched by any team in the Stanley Cup playoffs since expansion in 1967, the Devils are taking aim at hockey's ultimate prize.
Mounting tension over control and frontman status eventually proved insurmountable, aggravated by Phife's struggles with diabetes (his patient wife donated a kidney to him), and the group disbanded in 1998.
The government faces a formidable legal challenge in trying to persuade a federal judge to split up the Microsoft Corporation, but not an insurmountable one by any means, according to antitrust experts.
The Kiwis have parlayed their early leads into insurmountable advantages by showing an uncanny ability to sniff out the first wind shift on the inaugural leg, and pulling away from there.
