Hemingway set his stories in many different parts of the world, as pointed out by bullgatortail above. This use of setting lends his writing some international appeal as does his interest in the battles and conflicts of World War I and the Spanish Civil War.
The sense of creeping disillusionment that undergirds much of Hemingway's work probably also helps to create a general modernist appeal in his writing.
In part because he is one of America's greatest writers, Ernest Hemingway's stature as a literary giant has reached around the globe. National boundaries do not contain great writing, and Hemingway's popularity in other parts of the world are a testimony to the quality of his prose. I think his own personal exploits helped to create a larger-than-life image that became attractive to many prospective readers; but more importantly, Hemingway's settings encompassed many locales around the world. His stories are set in many different places, from the mundane to the exotic: Middle America, Florida, Cuba, Spain and Africa are just a few of the places that both Hemingway and his own fictional characters inhabited. Combined with his knack for great story-telling, it's no wonder that Hemingway's international reputation is as strong as in his homeland.