The phrase "assured fellow" is correct and usable in written English.
It can be used to describe someone who is confident and self-assured, often in a positive context.
Example: "He walked into the room like an assured fellow, ready to take on any challenge that came his way."
Alternatives: "confident individual" or "self-assured person".
A particularly assured fellow comes up.
But he assured fellow Republicans that he knew he could not deliberate too long and promised an unconventional candidacy should he become a contender.
Was it only a year ago that Prime Minister George A. Papandreou of Greece assured fellow participants that his country was on track to get its debt problems under control?
Most of these books aren't to be found at Amazon.com or Barnes & Noble, but be assured, fellow traveler, they are out there.
Iraqi officials have said the new plan is to use Iraqi units to force Mr. Sadr from the mosque, while assuring fellow Muslims, in interviews broadcast across the Arab world, that they will allow no damage to the shrine.
Mr. Sturgeon assured his fellow masons that photocopying will be prohibited, that all copies will be signed out and strictly audited.
Mr. Martonyi, however, assured his fellow European foreign ministers that the Fourth Amendment adds procedural guarantees to the church registration process, explaining that "an individual review of such decision can be sought before the Constitutional Court".
In a television interview granted to a broadcaster whose offices had been ransacked a few days before by policemen, he assured his fellow countrymen that there was "no emergency situation".
President Obama has pledged that a process of drawing down the additional "surge" forces he sent to Afghanistan will begin next month, and Mr. Gates said he had "assured my fellow ministers that there will be no rush to the exits on our part — and we expect the same from our allies".
Failures despite your having assured your fellow investors that each one had all the makings of a big success.
Rubin assured the Fellows that the abrasiveness Summers had exhibited at Treasury was a thing of the past.
