Yes, travel insurance is worth carrying for a trip built around Nejjo, a small town in Ethiopia's Kellem Wollega Zone in western Oromia: the honest case here is remoteness rather than any specific danger, since this part of the country sits a long way from the capital and its resources. Most travelers are here for aid or development work, agricultural business, or a stop en route further into western Oromia, and in every case a policy earns its keep the moment something goes wrong far from a major hospital.
Care standards vary sharply outside Ethiopia's larger cities, and Nejjo itself has only basic local health services for routine complaints. Serious illness or injury is typically stabilized on site if at all possible and then transferred, often over long unpaved roads, to Addis Ababa, the country's real medical hub. Look for a policy that explicitly names medical evacuation and transport between regional and capital facilities, since that transfer, not treatment in Nejjo itself, is the part that actually matters here.
Road access is the practical risk around Nejjo: routes through Kellem Wollega Zone can be rough even in good conditions, and Ethiopia's main rainy season, roughly June through September, regularly turns unpaved stretches to mud and can slow or cut off travel for days at a time. It is also worth checking current government travel guidance for this part of Ethiopia before finalizing plans, since advice for western Oromia has shifted at times, and a policy is only as useful as an itinerary that accounts for real access conditions on the ground.
Keep any local clinic paperwork, transport receipts, and records of delay if seasonal rains disrupt your route, since claims from an area this remote rely on documentation more than anything else. Check whether your existing health cover extends abroad and specifically to Ethiopia before assuming it does, since many home policies stop well short of a destination like this one. A standalone travel policy with genuine evacuation cover is the more reliable choice for an itinerary centered on Nejjo.